1. Field of the Invention
This invention relates to a new unsaturated carboxylic ester compound, particularly a polyfunctional unsaturated carboxylic ester compound, and a process for the production thereof. Since this unsaturated carboxylic ester compound has a photopolymerizable double bond, it can be advantageously used as a photocurable component and a reactive diluent, for example, of an actinic energy ray-curable composition which hardens by irradiation of an actinic energy ray.
The present invention further relates to a curable composition containing the above-mentioned unsaturated carboxylic ester compound, which composition hardens promptly by irradiation of an actinic energy ray such as an ultraviolet ray or an electron beam or further hardens by heating, thereby giving rise to a cured product excelling in adhesiveness to a substrate, particularly a composition curable with an actinic energy ray. This composition can be used in various application fields as adhesives, coating materials, and resist materials for printed circuit boards.
2. Description of the Prior Art
The curing of resin by irradiation of an actinic energy ray is widely utilized in painting of metal, coating of wood, printing ink, electronic materials, etc owing to its high curing speed and solvent-free. One of the materials mainly used in these fields is an epoxy acrylate. Since this compound is obtained by the reaction of an epoxy resin having an oxirane group which is a cyclic ether of three-membered ring and (meth)acrylic acid and contains a polymerizable unsaturated group, it is used in a photocurable composition by mixing with a compound which generates radicals by irradiation of an actinic energy ray (phtopolymerization initiator), and heretofore various studies thereof have been done. However, the composition containing this compound had the problem of being inferior in the adhesiveness to various substrates because the composition causes large shrinkage after photocuring and most of the hydroxyl groups caused by the modification reaction of an epoxy resin are secondary hydroxyl groups. For the purpose of solving such problems, the composition which employs the cationic polymerization of oxetane as a curing reaction has been proposed. However, the kinds of materials which can be used in this reaction are small in compared with a radically polymerizable monomer, it was possible to attain the desired properties of the cured product only with difficulty.
On the other hand, the organic reaction involving the addition reaction of an oxetane ring which is an ether of four-membered ring has been reported recently. For example, the addition reaction of an oxetane compound and an active ester (T. Nishikubo and K. Sato, Chem. Lett., 697 (1992)) and the synthesis of polyester having a primary hydroxyl group attached to a side chain thereof by the polyaddition reaction of a bisoxetane and a dicarboxylic acid (T. Nishikubo, A. Kameyama, and A. Suzuki, Reactive & Functional Polymers, 37, 19 (1998)) have been reported.
Furthermore, JP 10-168120, A discloses a method of producing a resin of the actinic energy ray-curing type by carrying out ring opening addition of an oxetane group-containing (meth)acrylate monomer to a carboxyl group-containing resin or by effecting ring opening addition of a carboxyl group-containing unsaturated monomer to an oxetane ring-containing resin. However, these articles make no mention of the compounds of the present invention and the actinic energy ray-curable compositions using them.